This proposal will test the following hypothesis: 1) NAA and advanced changes in Alzheimer's disease are more pronounced than in age related controls; 2) the degree of cognitive decline in Alzheimer's disease as measured by neuro-psychological tests will correlate with the severity of NAA depletion and GLU increase; 3) patients undergoing cholinergic therapy over a period of one year will show a less severe decrease in NAA and increase in GLU.